In the normal course of operation, the electronic Integrated Circuit (“IC”) chips that are comprised by computer hardware generate heat. In CMOS and related technologies, the heat generation is a function of the rate of state transitions per unit time, so as software tasks are handled there are frequent, rapid increases and decreases of emitted heat from a given chip as computers operate. Additionally, as heat builds up in CMOS and other semiconductor devices, leakage currents typically increase, creating yet more heat.
Data Centers
The amount of heat generated is considerable even when only one computer is involved. In the case of server farms and other data centers the heat generation problem assumes vast proportions. Most of the heat in data centers is removed by costly and relatively inefficient means that also consumes yet more energy and generates yet more heat. Unlike many industrial processes where waste heat is harnessed for site-based energy reuse of power-cogeneration, most of the heat in data centers is simply dissipated into the environment.
Providing a cost-effective, efficient and practical solution to this IC-chip and electronic component generated heat is therefore crucial. As cloud computing, search, download, and other network services radically increase centralized computing demands, creating needs for computation and data centers to becoming larger and larger, the need for massive facilities increases, causing the magnitude of the heat generation problem to become increasingly urgent.
The increasing demand and trend to ever-larger and more robust computer data centers necessitates that the industry practice of utilizing cheap, passive traditional thermal design be replaced with more advanced thermal technologies.
Leveraging Data-Center Turn-Over to Rapidly Introduce Cooling and Energy Harvesting Technologies into Data Centers
Fortuitously, new inventions (such as the present invention) that address these problems all or in part can conveniently take reliance upon Moore's Law (which observes that approximately every 18 months computer power doubles while the cost roughly halves) and ongoing changes in computer server architecture. The resulting combined forces of natural degradation and functional obsolescence force computer hardware (data center hardware in particular) to naturally be replaced or upgraded on a periodic basis. As each hardware replacement cycle brings in new computer hardware, this allows new cooling technologies to be introduced.
Approaches to Reduce Heat Production in Integrated Circuit Operation
A large number and wide variety of approaches are currently under research, development, and deployment to reduce heat production in integrated circuit operation. A brief survey of these very active areas can be found in [1], Chapter 1, and the material there is summarized in the list below:
Dynamic Power Consumption                Reducing Capacitance        Reducing Switching Activity        Reducing Clock Frequency        Reducing Supply Voltage        
Static Power Consumption                Leakage currents arise from the flow current across a transistor even when the transistor is in an OFF state.        Gate-oxide leakage is dependent on the thickness of the oxide that is used to insulate the gate from the substrate. As process technologies are decreasing, so is the gate-oxide thickness. Higher k dielectrics will have to be used to offset sub-threshold leakage. Flow of current between the drain and source of a transistor when the voltage is below threshold.        
Circuit-Level Power Consumption in Integrated Circuits                Transistor Reordering        Half-Frequency and Half-Swing Clocks        Low-Power Flip-Flop Design        Technology mapping automates the process of producing a power-optimized circuit in order to minimize the total power consumption.        Bus Inversion        Crosstalk Reduction        Low-Swing Buses        Segment the bus into multiple groups that allow the majority of the buses to be powered down while only the active buses are in use.        Adiabatic circuits are a novel concept that reuses the electrical charge dissipated from one wire and recycles it for use in another wire        replace the traditional shared-bus approach with a more generic interconnect network.        
Low-Power Memory Design                Partitioning Memory        Specialized Power-Friendly Caches                    Filter cache            Trace cache            Adaptive caches            Drowsy cache                        
The present invention is not directed in these directions, but rather as to what to be done with the electronic-component heat that must be generated, regardless of its source or cause, The present invention addresses this on several fronts:                Improved heat transport, aggregation, management;        Component thermal environment improvement;        Consideration of the full heat transport hierarchy;        Adaptive opportunistic energy harvesting;        Leveraging reciprocal (heat transfer, heat to electrical current conversion) properties of both classical semiconducting thermoelectric devices and quantum-process thermoelectric devices;        Adaptively switching modes and/or multiplexing between cooling mode, energy-harvesting mode, and temperature sensing modes;        In switching among modes and in general operation, including consideration of and/or compensation for the dynamic behavior of the thermoelectric devices employed;        Various control systems to manage local and system-wide operation. Computer System Cooling Technologies        
A large number and wide variety of approaches are currently under research, development, and deployment to reduce, manage, and handle heat build-up in integrated computer systems and data centers. A survey of the many well-known classical and contemporary techniques for this these at the board and chassis level can be found in [2] and the references therein. A representative treatment of the many well-known and contemporary techniques for this these at the data center level can be found in [3]-[4], these largely involving forced air and chiller technologies. The present invention provides economical practical near-term supplements, enhancements, and alternatives to these approaches, including for example the invention innovations listed in the previous subsection and called out in bold font in FIG. 3.
Chip Cooling Technologies
A large number and wide variety of approaches are currently under research, development, and deployment employing thermoelectric devices. A survey of the many well-known classical and contemporary techniques for these employing semiconducting thermoelectric devices can be found in [5] and the references therein. A brief treatment of techniques and properties of quantum-well thermoelectric devices can be found in [6] and the references therein. Treatment of techniques and properties of Avto metal thermoelectric devices can be found in [7]-[10] and the references therein. Additionally, micro-droplet microfluidic cooling is also currently under research and development, some employing some minor interworking with thermoelectric devices. Treatment of such approaches employing planar (two-dimensional) micro-droplet transport can be found in [1] and the references therein, and approaches employing three-dimensional and multiple-layer micro-droplet transport are taught in U.S. Patent Application 61/599,643.
As background, FIG. 1a depicts an exemplary computer processor chip fitted with a traditional air-cooled finned heat sink. In practice the depicted cooling fins can be much larger than depicted here. One or more fan(s), each within or attached to a chassis which envelopes an associated computer processor chip, are used to force incoming air through and/or over the heat sink. The forced air absorbs heat radiating from the fins of the heat sink, transporting it away from the chip and thus preventing a higher degree of heat buildup. FIG. 1b shows an arrangement like that of FIG. 1a but fitted with a dedicated fan to increase the air flow through the air-cooled finned heat sink. FIG. 1c shows an arrangement like that of FIG. 1b but with a thermoelectric cooler layer provided to increase the heat flow from the Integrated Circuit chip to the air-cooled finned heat sink. FIG. 1d shows an arrangement like that of FIG. 1c but with a dedicated fan to increase the air flow through the air-cooled finned heat sink.
FIGS. 1e-1g depicts various alternative chip cooling arrangements wherein heat pipes are used to transport heat away from a computer processor chip. FIG. 1e depicts an exemplary heat pipe system employed in a laptop computer. FIG. 1f depicts an exemplary heat pipe system wherein the heat pipe connects transferred heat produced at the chip to a fan-cooled heat-sink. FIG. 1g depicts an exemplary arrangement heat pipe system wherein a principal heat sink is connected via heat pipes with expansion heat sinks.
Hierarchy of Heat Transfer in Data Center Environments
As yet further background, FIGS. 2a-2g illustrate a hierarchy of environments involved in heat transfer.
FIG. 2a shows a group of computer chips and related components (for example, voltage regulator components), for example, on a common printed circuit board. These are the primary source of heat generation, although heat is also generated by other elements such as power supply transformers and circuitry, fans, compressors, chillers, pumps, etc. included in cooling systems.
FIG. 2b depicts the two or more such groups of computer chips and related components, for example, sharing a common printed circuit board.
FIG. 2c illustrates two or more printed circuit boards, either as in FIG. 2a or FIG. 2b, which together are comprised by a common subsystem. FIG. 2d illustrates two or more subsystems, such as depicted in FIG. 2a or otherwise, which together are comprised in a common chassis. Such a chassis can be part of, for example, a computer server.
FIG. 2e shows a plurality of chassis comprised by a cage. Such arrangements are used in commercial “blade server” product configurations.
FIG. 2f depicts a plurality of cages, such as depicted in FIG. 2e or otherwise, fitted into a rack. Such rack configurations are used endemically in data centers. FIG. 2g represents a cluster of racks as commonly used in data centers.
Overview of the Innovation
The invention comprises a collection of interworking innovations. These include:                Systems and methods for combining Peltier-effect heat transport and Seebeck-effect energy harvesting for use at thermal interfaces in heat gathering and transfer structures;        Novel structures for multiple-mode thermoelectric devices providing heat transfer, heat-to-electricity conversion, temperature flux measurements for use in interfacing integrated circuit packages and in creating active heat pipes;        Arrangements in the above permitting simultaneous mixed-mode operation        Automatic control for optimizing multiple mode and mixed-mode operation in local or hierarchical contexts;        Pulse-width modulation and other duty-cycle control to prevent Peltier cooling induced condensation;        Use of traditional, contemporary, and emerging quantum-process and nanomaterial techniques for radical efficiency improvements in Peltier-effect heat transport and Seebeck-effect thermoelectric energy harvesting;        Configurable, reconfigurable, or real-time-controlled selective operation of combined Peltier-effect heat transport and Seebeck-effect thermoelectric energy harvesting;        Systems and methods for a modular-structure heat gathering and heat transfer infrastructure designed, for example, to work with existing familiar board, blade, cage, rack, data center, and building infrastructure, the systems and methods supporting optional advantageous additional features of:                    Closed heat transport systems within each module terminating in a thermal interface which can be coupled to external heat transport stage, air cooling, energy transformation, or other alternatives;            Each module equally usable in isolation or as part of a hierarchy, allowing wide range of gradual phase-in deployments, trials, and strategies;            Internal energy harvesting within the module;                        Hierarchical heat-gathering structures with dry thermal-transfer interfaces between pairs of closed level-internal cooling fluid and heat pipe structures within modules at each layer and fan backup for isolated operation or parent-level failure recovery;        Hierarchical heat-to-electricity energy harvesting structures with provisions for both local use of heat-harvested electricity as well as provisions for exporting power into hierarchical or peer arrangements;        Hierarchical control structures capability of working in isolation or coordinating with other control systems in hierarchical or peer arrangements.        
FIG. 2h depicts a representation implying the innovation can be utilized when a data center occupies one or more whole or partial floors of a building and/or a vertical riser within a building. FIG. 2i depicts a representation implying the innovation can be applied when a data center occupies an entire building. FIG. 2j depicts a representation implying the innovation can be utilized when a data center is comprised of a campus of buildings.
FIG. 3 depicts an exemplary non-limiting, non-characterizing view of various aspects of the invention. The invention combines many new innovations (denoted by bolded font) together with novel utilizations and adaptations of known art (denoted by unbolded font).